HRT team principal Colin Kolles has signalled his intention to protest against the use of off-throttle exhaust configurations at the Monaco Grand Prix.

The FIA had moved to outlaw teams using exhaust gases to blow their diffusers at more than 10% of full throttle, initially planning on introducing the ban ahead of the Spanish Grand Prix. However, the use of sophisticated engine mapping makes an immediate change difficult, and the governing body granted the teams more time last week.

FIA technical delegate Charlie Whiting admitted, however, that the practice could be deemed illegal and that it was open to be challenged. HRT was one team not to run a new diffuser in Barcelona in response to the upcoming ruling as any development in the area would come at great expense. Kolles said he would protest against the legality of any cars using the system if it wasn't banned by the FIA before the next race.

"This is illegal," Kolles told the BBC. "You cannot influence the aerodynamics by hot exhaust gases or any moveable devices. We have studied this very carefully. The point is it is not corresponding to the regulations. It brings the other teams a huge advantage.

"We agree absolutely with Charlie Whiting's view and, by the way, we are not the only ones who agree. I think that if this is not going to be stopped before Monaco we have no other choice than to make a protest"

Kolles said he did not know whether he would launch a protest before or after the next race, but that he had refrained from doing so in Spain having not been competitive during the race.

"I cannot tell you at what stage during the Monaco Grand Prix. The only reason why we are not considering it [protesting after the Spanish race] is because we were not involved in any sporting decision today."

As the only team on the grid that isn't a member of FOTA, any protest would further distance HRT from the rest of the paddock. In order to avoid the issue getting that far, Kolles told the Press Association that he had written to Jean Todt to get changes made before Monaco.

"We have written a letter to the president of the FIA asking for the exhausts to be banned immediately because they are against the regulations. The letter has been signed and sent. I'm obviously expecting a response before next weekend's race."